Automatic stop for sewing machines



June 23, 1953 M. s. MANSSON 2,643,305

AUTOMATIC STOP FOR SEWING MACHINES 7 Filed 001;. a, 1949 2 Sheets-Sheet 1 INVEN TOR.

Mgr/m a. nfw/ssa/v June 23, 1953 M. s. MANSSON 2,643,305

AUTOMATIC STOP FOR SEWING MACHINES Filed Oct. 6, 1949 2 Sheets-Sheet 2 W 6 Q. f XY- 5 JNVENTOR. M/em a M44650 firraewsy Patented June 23, 1953 UNITED STATES PATENT OFFICE AUTOMATIC STOP FOR SEWING MACHINES Martin S. Mansson, Long Island City, N. Y.

Application October 6, 1949, Serial No. 119,980

(Cl. ZOO-52) 12 Claims.

The present invention is directed to circuit closing devices of sensitive nature, more particularly to a device of this kind adapted for breaking the circuit of a sewing machine motor in order to stop the operation thereof.

In modern high-speed sewing machines, it is necessary to provide safeguards so that when there is an accidental defect in the operation, the machine may be stopped at the earliest possible moment. For instance, it often happens that in the operation of the sewing machine, an irregularity occurs whereby the thread may skip a stitch. This, of course, is undesirable and the machine should be stopped when this occurs in order to adjust the same properly. However, in the past, no satisfactory device for stopping a machine under these circumstances has been on the market.

It also happens quite frequently that a bobbin thread runs out and it may be some time before 7 the operator notices it so that a defective piece of stitching results. bobbin thread breaks as the operator, not being in a position to notice the running out or breaking of the thread, will not become aware of it until considerable damage has been done.

The present invention is intended and adapted to overcome the difliculties and disadvantages of the prior art, it being among the objects of the invention to provide a simple, compact and sensitive arrangement which will stop the motor of a sewing machine when a bobbin thread runs out or when a thread skips a stitch.

It is also among the objects of the present invention to provide an arrangement which may be attached to the head of a sewing machine and which is operated by the thread passing through the sewing machine needle. 7 7

It is further among the objects of the present invention to provide a switching arrangement of the type described, which is compact and which is adapted for various uses where a current is to be made or broken under special con ditions.

In practicing the invention, and particularly in connection with a sewing machine, there is provided a pressure sensitive member which may be in the form of a wire placed in a position in back of and adjacent to the needle and the thread passing therethrough. When the sewing machine is operating normally, the thread does not contact the pressure sensitive member but when the machine skips a stitch, the thread is pulled in the direction of the member and in making contact therewith, operates the mechanism which eventually opens the motor circuit and stops the machine. Similarly, when the bobbin thread runs out or breaks, the needle thread is pulled in the direction of the sensitive The same occurs when the member and operates the switch mechanism to stop the motor.

There is provided a receptacle with a shaft pivoted on one of its walls and the pressure sensitive member is secured to the shaft on the outside of the receptacle. The shaft also has an extension within the receptacle, said extension having an open end in the nature of a slot or a slit. In proximity to said slot is a stub shaft which is also pivoted in the receptacle and this has a movable contact member secured thereto. The contact member lies close to and approximately parallel with the extension.

A projection on the movable contact member and adjacent to the stub shaft has its end inserted into the slot of the extension. Thereby upon the movement of the pressure sensitive member, this shaft oscillates, causing the extension to move the projection and thus cause the movable contact to engage with or disengage from a fixed contact which is also mounted in the receptacle. A single wire is usually electrically secured to the fixed contact to form part of the circuit and a second wire is dispensed with as the metal members complete the circuit. Usually a cover, transparent in character, closes the open face of the receptacle.

In the accompanying drawing constituting a part hereof and in which like reference characters indicate like parts,

Fig. l is a front elevational view of a device made in accordance with the present invention and shown as attached to the head of a sewing machine;

Fig. 2 is a side elevational view thereof;

Fig. 3 is a view similar to Fig. 1, showing a modified form of the arrangement of elements within the receptacle;

Fig. 4 is a vertical cross-sectional view through the housing, and

Figs. 5 and 6 are side and front views of a modification.

The arm I of a sewing machine has the usual sewing head 2 containing the sewing instrumentalities including a presser foot bar and a needle bar. The sensitive arrangement is secured to a stationary part of head 2 and includes a receptacle having an annular housing 3 having a disk-like base 4 with a cover plate 5 of insulating material. The cover is secured to the base by set screws 6.

A shaft 1 passing through base 4 is covered by cap 8 secured thereto by set screw 9. A wire it passing through an opening in cap 8 is held in adjusted position by set screw H. The lower end I2 is in the form of a horizontal bar in proximity to the needle. On shaft 1 within the receptacle is an extension [3 fixed to the shaft and having at its left hand end a slit or slot or opening 14.

Just beyond slot i4 is a stub shaft l5 having the base I 5 of a contact member I fixed thereon. A projection [8 extends into slot l. Contact I9 is secured to H near its outer end. As shown in Fig. 1, contact member H is substantially parallel to and overlies extension 13, thus providing a very compact arrangement. Because of the several lever arms involved, a very slight movement of wire In will cause a-positiveemovementr of movable contact is.

Within the receptacle and just abovestub shaft 55 is plate 2i] having a slot..2l. therein held to base 3 by suitable means such as a set screw. A hairspring 22 has one end secured in plate- 20 and is looped in the form of an arc with its end 23in theform'ofa reverse curve or V incontact. Thespring;

with the end of contact member ll. has :the function. of i retaining; the. contact positivelyin both, open and closed. positions. Be.-

causeof the. screw and slot arrangement, the positionandtension of hairspring22 maybe-adrjustedz.

A, stationary contact 24 justabove movable contact leis held onmemberZE-securedto cover platesfi by ascrew 25: A capv 21 is adapted to frictionally engage the-outer end of screw 26 and carries 21:; wire for making an electricalconnection to the fixed contact, The movablecontact I 9' hasmo: wire-associated with it but is. grounded on the: metal parts: of: the: machine itself To? the outer: surface; of. base i-iis-secured a bevelledxfiat plate :2 8 and an angular, member. 2 9- issecureditoplate 28-.by screws 39. The'other angleof said; plate constitutes a finger 31 for. contacting. withthe presser foot bar. member: 2.3; is adaptedwto'slide ina groove 32; of bl0ck2g33r. Around screw 3% on block 33 is secured oneiend. of :azwire: spring 3.5" which passes around screw 35:. andrthgother end 37 rests-upon. pin .38

Thetension of.- the springissuchasto tend to. force tongue:-28: down wardly. A pin 39=on the-backbf tongue 28 is.

in, the; front; of; tongue: 28..

adaptedtocontact-the body of -block33-tov act as a stop, limitingthe'downward-movement of 28;

At the rear of block Skis.- a complementary blockor clampflfisecuredxto-block 33 by screws 4|.

lifted simultaneously and; this; raises receptacle;

3 up: with it, thus'gallowing fullaccess-to thesfabric. being sewn;

Angular At. the junctionof 3.35and Clilarev a pairrof; recesses; or openings 42 partially in each of the In .the operation of the device during thenor- I mal ,use' of the-sewing machine, the. elementsare in .thepositionsshown in Big. 1 with thethread 48 extending. substantially vertically downward from the eye of the needle andinto. the: fabric beingv operated on. The" several. elements 1 of. the

switching arrangement are also in, thesp osition.

shown .inFig. 1, withmovable contact, li spaced from stationary contact 25. shouldrun out orbreak, thread. 43 moves rearwardly, taking the position 38', as shown in Fig. 1, contacting. with bar 52. of wire it. atmovement. to the. rearof wire I0, causing extensions l3 to pivot upwardly on shaftl, This.

If the bobbinlthread.

This causes.

in turn causes projection Hi to be raised, rotating stub shaft l5 and raising contact member H. The force is sufficient to cause the end of said contact member to rise past the V-shaped portion 23 of-hairspring;22-, thus. closing the circuit. Current passing through the circuit may be utilized to operate a relay which in turn opens the motor circuit of the sewing machine and thusrstops' the. operation thereof.

In the modification shown in Fig. 3, in place of extension l3 which is in the form of a fiat bar, there. may. be. provided a U-shaped member 49, the central part of which embraces shaft l and is 'fixed'thereto as by soldering. The ends of the legs of the U define a slot or opening 50 into which projection; l8 extends; The: several elements are,shown; in the-position they assume; when the. switch circuit is closed and themotor. isstopped.

In Figs. Sand 6: is;shown.a..clamp .5! held on. bushing;.52*bysorews. 53. Abracket 54; integral with the: clamp, extendsrearwardlyand an .:arm 551s: pivoted,- thereto -by-- pin .56. Plate 51 fixed, on. the free. end, of arm. 55 -has a projecting, lug; 58- adaptedto contact-the top 59- of=the presserfoot. Projection. 60. on bracket 54, limits. the: downward. movementof the. arm and spring. 6| tends to maintain. the arm in the position shown.

Although the invention has. been: described. settingforth-several specific embodiments there-- of, various changes in thedetailsofthe construction may be. made. without. departing. from= the.- principles herein set forth. For instance, cover;

' 5 of insulating: material is.- sometimes. made transparent.- bu-tit I may; be.- opaque-,-, if; desired. Receptacle 3; is, illustratedas. being circular in: shape -but-va-rious other shapesrmaybeusubsti-- tuded for. it. Thesrelative. positions 10f the parts. within. the receptacle; may" beqconsiderably, a l-.- tered; while; retaining; theTcompactearrangement, all within. the. scope of, the invention. The meanssfor mounting.,the,;pressure;sensitivedevice may be-differenty from thatshowniand, forinstance,v block.- 33 may. be. directly secured tohead' 2 without the. necessity of. aeclamping. arrange.- ment. The :deviceitself apart. from .theemounta ing means maybe-used in: various. applications Where a pressure sensitive=means for openingand. closing a. circuit-is .desired; Y

These: and other. changes may bemade within: the spiriteoftheinvention, which.is;to be-broadly. construed andinots to be limitedv except. bythe.- oharacter of the .claimsxappended hereto;

I..claim;.

1. A. sensitive mechanism. for: controlling an: electricalioi-rcuitsuchqas thatzof a: sewing; ma-" chine; motor; comprisinga receptacle, a. shaft.

pivoted; within and ,on a; wall thereof and having.- a pressure sensitive member secured thereonon. the outside. of. saidreceptaclerand. adapted to contact with; athread under tension. and to. be; moved thereby, anextension on said shaft in. said. receptacle, a stub shaftpivotedin said receptacle; in proximity to. the. free.v end. of said 7 extension, a movable contact member. secured to. said stub, a. projection. on; said movable; contact. cooperativelyv attached. to the; end of. said extension, whereby oscillation .of. said shaft. causes oscilla tionof saidlstub shaft and movable contact, a. fixed. contact in proximity to said. movablev con tact and adapted to close. a circuit therewith, and. aspringone end of which is .attachedto said receptacle and the-other. end having v an. angular portion .in. saidzreceptaole 1 enga ing, the .-fr.ee.=- end.

of said movable contact to maintain it in open and closed positions alternately.

2. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a. wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, said movable contact overlying said extension, and a spring one end of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of said movable contact'to maintain it in open and closed positions alternately.

3. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable cont-act cooperatively attached to the end of said extension, whereby oscillation of said shaft causes 0scillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, said movable contact overlying said extension and said fixed contact overlying said movable contact, and a spring one end of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately.

4. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end of which is attached to said receptacle, the free end of said spring in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, said spring being a hair spring having an angular portion engaging the free end of said movable contact.

5. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to cont-act with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end of which is attached to said receptacle, the free end of said spring in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, said spring being a hair spring having an angular portion engaging the free end of said movable contact with means for adjusting the position of said spring to vary the tension thereof.

6. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub,

a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end of which is attached to said receptacle, the free end of said spring in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, said spring being a hair spring having an angular portion engaging the free end of said movable contact, means for mounting said spring in proximity to said stub, said spring being in an are around said fixed contact.

7. A sensitive mechanism for controlling an electrical circuit such as that of a sewing machine motor oomprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle in proximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, a base adapted to be secured to a machine head, said receptacle being mounted on said base.

8. A sensitive mechanism for controlling an 7 electrical circuit; such as," that of'a sewing machine: motor comprising a receptacle, a shaft pivoted withinand on .awall thereof andhaving a-pressure sensitivemember secured. thereon on the outside of said receptacle and adapted to contact with a thread under tension. and to bemoved thereby, an extension on said shaft insaid receptacle, a stub shaft pivoted-in said receptacle inproximity'to the free end of said extension, a

movable contactmember secured to said stub, ay

projection on said movable contact cooperative I 1y" attached to the end of said extension, wherebyoscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted'to closea circuit therewith, and a spring'one end of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of'said movable contact to maintain it in open and'closed positions alternately, a base adapted chine motor comprising a receptacle, a shaft pivoted within and on a wall thereof and hay-- ing" a pressure-sensitive member secured thereon on the outside of said receptacle and adapted to contact'with-a thread under'tension and to be moved thereby, an extension on said shaft in I saidreceptacle', a'stub shaft pivoted in said. re-

ceptacle in proximity to the freeend of said ex--- tension, a movable-contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed'contact inproximity to said movable contact and adapted to close acircuit therewith, and a spring one end of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, a base adapted to be secured to a machine head, said receptacle being mounted on said basefor vertical movement relativeto said base, means for biasing said receptacle downwardly relative to said base-and a' stop-for limiting the downward motion of'said receptacle.

10. A sensitive mechanism for controlling an electrical cirouitsuch as'that of a sewing machine motor, said machine having a presserfoot, comprising a receptacle, a shaft pivoted within and on a wall thereof and having a pressure sensitive members secured thereon on the outside of said receptacle and adapted to contact'with a thread under tension and to'be moved thereby, an extension on said shaft in said receptacle, a stub shaft pivoted in said receptacle inuproximity to the free end of said extension, a movable contact member secured to said stub, a projection on said movable contact cooperatively attached to the end of said extension, whereby-oscillation of said shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end. of which is attached to said receptacle and the other end having an angular portion in said receptacle engaging the free end of said movable contact to maintain it in open and closed positions alternately, a base adapted to besecured to a machine head, said receptacle being mountedon said base for vertical'movement relative to said base, means for biasing said receptacle downwardly relative to said base and. a

stop for limiting the downward motion of said receptacle, and a finger fixed on said receptacle adapted to engage said presser foot and to be lifted by the movement thereof.

11. A sensitive mechanismcfor controlling an electrical circuit such as that of a sewing machine motor comprising a receptacle, a shaft pivoted within and on a wall'thereof and having a pressure sensitive member secured thereon, on thev outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension onsaid shaft in'said receptacle, a stub shaft pivoted in said receptacle in proximity to the free endof said extension, an movable contact member secured to said stub', a-

projection on said movable contact cooperative,- lyattached to the end of said extension, whereby oscillation of said shaft causes oscillation of.

said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit therewith, and a spring one end of which is attachedto said receptacle and the other end having an angular portioninv said receptacle engaging the free end of said' movable contact to maintain it in open and closed positions alternately, a base adapted to be secured to a machine head, said receptacle being mounted on said base for'verticalimovement relative to said base, and a tongue and groove ar rangement on said receptacle and base adapted to provide said vertical movement.

12. A sensitive mechanism for'oontrolling an:

electrical circuit such as that of a sewingmachine motor comprising a receptacle, a shaft pivoted within and on a wall thereof andhav ing a pressure sensitive member secured thereon on the outside of said receptacle and adapted to contact with a thread under tension and to be moved thereby, an extension' on said shaft in said receptacle, a stub shaft pivotedin said receptaclein proximity to the-free end ofsaid extension, a movable contact member se curedto said stub, a projection on said-movable contact cooperatively attached to theendof said extension, whereby oscillation of said' shaft causes oscillation of said stub shaft and movable contact, a fixed contact in proximity to said movable contact and adapted to close a circuit:

therewith, and a spring one end of which is'attached'to said receptacle and the'other end hav-- ing'an angular portion in said receptacle engag--- ing the free end of said movable contact to main-- tain it in open and closed positions alternately, a base adapted to be secured to a machine head,

said base having recesses therein and a clamp adapted to embrace a part of said machinehead, said receptacle being mounted on saidbase.

MARTIN S. MANSSON.

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